Ramble Report May 16 2019

Today's Ramble was led by Linda Chafin.

Here's the link to Don's Facebook album for today's Ramble. (All the photos in this post are compliments of Don, unless otherwise credited.)

Today's post was written by Linda Chafin.

29 Ramblers met today.

Today's focus:  Cool-season grasses along the White Trail and in the powerline right-of-way.

Show and Tell:

Halley brought a section of tree top that recently fell in her yard.  It was a hollow section with a large hole for a woodpecker nesting cavity.  Eugenia thinks it may be a Red-bellied Woodpecker (Melanerpes carolinus) nest.

Announcements: Tomorrow (Saturday, May 18) is Snake Day at Sandy Creek Nature Center (12 to 4 p.m.)  Bring the children or grandchildren!

Today's reading: Bob Ambrose recited his new poem, Lament for a Rose-breasted Grosbeak, inspired by the death of a bird Bob reported at last week’s ramble.

Today's Route:   We left the plaza, heading down the road towards the White Trail crossing from the Dunson Garden to the right-of-way.  We took a right on the White Trail and, after entering the ROW, got off-trail and walked up the right side of the ROW in the tall grasses as far as the Square Meter plot.  Don introduced the Square Meter plot project: he, Linda, and Dale have selected and flagged a square meter in the ROW that they will observe, photograph, and describe throughout the year, similar to the Southern Appalachian project described in David George Haskell’s book, “The Forest Unseen.” We turned around at that point and returned to the Visitor Center the way we came.  We then enjoyed the post-Ramble social hour at the Café Botanica before many of the Ramblers adjourned to the adult classroom for the monthly book club meeting.

Cool-season grasses: what they are and why we care.

Today’s Ramble focus was cool-season grasses, i.e. grasses that flower and go to seed in the spring. After dispersing their seeds, cool-season grasses slow or cease their growth until cool weather returns in the fall; many remain green during the winter.

The grass family, Poaceae, is one of the largest of all plant families, with about 12,000 species. Cool-season grasses include many of the world’s most important agricultural crops: rice, wheat, barley, rye, oats. Warm-season grasses, such as bluestems, wire grass, and cordgrass, are keystone species in several of Georgia’s natural communities.

Grasses, which are in a plant family all their own, are often confused with grass-like plants from two other families, the sedges and rushes. To keep them separate, we invoke the old jingle: “sedges have edges, rushes are round, and grasses have joints all the way to the ground.” The last part of that is sometimes given as “and grasses like glasses are hollow,” not quite as poetic but also accurate. Sedges typically have pith-filled, three-angled stems, hence “sedges have edges.” Rushes have round stems. Grasses, on the other hand, have round, hollow stems except at the solid, pith-filled leaf nodes, called joints.

Cross-section of Cherokee Sedge stem, showing the three-angled stem.
(click to enlarge)

Rounded stems of Path Rush, a common upland species.(click to enlarge)

There are many other important differences among these three families, especially in flower and fruit structure. These families do have one important trait in common: all are wind-pollinated and, having no need to attract pollinators, have small, green flowers (or florets) that don’t produce nectar or pollen. Early in the season, stamens may be seen dangling from the spikelets, where the wind easily catches the pollen, and brush-like stigmas protrude from the spikelet, combing pollen from the air.

Dangling stamens and brush-like stigmas take advantage of the wind for pollen dispersal and capture.
(click to enlarge)

Like all plants, grasses take up carbon dioxide and water and, using energy from the sun, make carbon compounds in a process called photosynthesis. All cool-season grasses, as well as the vast majority of other plants, conduct photosynthesis in a method called “C3 photosynthesis,” so called because the first carbon compound produced during photosynthesis contains three carbon atoms. In contrast, warm-season grasses, which flourish in the high temperatures and often droughty conditions of late summer, use C4 photosynthesis which produces more carbon compounds with less water loss during the process. C4 grasses dominate in tropical and warm-temperate zones; in Georgia, they include broom sedge grass, bluestems, plume grasses, cordgrasses, and many more.

Grasses come in two growth forms: turf and bunch. All of Georgia’s native grasses are bunch grasses whose clumps provide good nesting and cover sites for wildlife and leave ground-level space between clumps for small animals to forage and travel. Bunch grasses typically have very deep root systems. Turf grasses such as Bermuda and St. Augustine have shallow roots and form dense sods that are not very useful to wildlife.

The hardest part about learning to recognize grass species is the whole new vocabulary involved with naming the parts. Here are two helpful diagrams:

Grass Terminology
(Photos by Den Tenaglis, Missouriplants.com)
(click to enlarge)

Grass flower terminology
(click to enlarge)

Some cool-season bunch grasses at the Botanical Garden:

Orchard Grass is found in many disturbed habitats, such as roadsides and pastures; at the Garden you can see it along the road to the Mimsie Lanier Center. Orchard Grass was introduced from Europe as a forage and hay species–livestock love it–and for erosion control. Its leaves are bluish-green and the base of the stem is somewhat flattened (but not 3-sided!). The flower cluster is more or less triangular in overall outline. The flower cluster is made up of small clusters of spikelets that often have a reddish tinge, especially in full sun.

Orchard Grass spikelets (and a Daddy Longlegs)
(click to enlarge)

Meadow Fescue is also native to Eurasia and was introduced for forage and hay. It is common in the powerline and is being removed as the right-of-way is being converted to prairie species. Its leaves and stems are grayish-green. The leaf nodes (joints) are especially swollen. At the junction of the blade and sheath, there are a pair of tiny, white structures called auricles–these are very helpful in identifying this species. The flower clusters are held upright and contain many erect spikelets. There are usually no awns on the spikelets.

Meadow Fescue flower cluster
(click to enlarge)

Brome Grasses in our part of the country are largely imports. Two species occur along the White Trail and in the powerline right-of-way: Rescue Grass and Rye-brome Grass. Rescue Grass, from South America, has very hairy leaf sheaths and open, airy flower clusters. The branches within the cluster are long, delicate, and drooping, and bear flattened, pointed spikelets that are two-toned green and pale yellow. Rye-brome Grass looks similar but its spikelets are solid green and cylindrical rather than flattened and two-toned, and have long awns, giving the spikelet a bristly look.

Rye Brome Grass
(click to enlarge)

Witch Grasses bloom once in the spring and again in the fall, proving once again that there are always exceptions to the rules that humans devise to categorize plants. Witch-grasses are distinguished by their small, very open and airy, flower clusters. The branches within the cluster are very delicate and wavy, each tipped with a very small, round spikelet.

Witch-grass spikelets with purple stigmas exserted to catch wind-blown pollen
(click to enlarge)

Witch-grasses are mostly hard to identify to species but two common species are relatively easy: Velvet Witch-grass and Deer-tongue Witch-grass.

Velvet Witch-grass has very hairy stems and leaf sheaths and a small hairless band at the node.

Photos by Dan Tenaglia, Missouriplants.com.

(click to enlarge)

Deer-tongue Witch-grass leaves are somewhat heart-shaped, with the base clasping the stem. The sheaths and stems are hairy, but not as hairy and velvety as Velvet Witch-grass.(click to enlarge)

Little Barley is a native species in the same genus as the cultivated barley (from Europe) used to make scotch and barley soup. This is an annual species that comes and goes around the Garden; this year I found it in the parking lot next to the powerline. Although tiny, its seeds were eaten by Native Americans. Its pale green spikelets are held in an erect spike which is distinguished by the many awns that give it a bristly look.

Little Barley seed heads
(click to enlarge)

Oat-grasses are common native species found in dry or poor soils. Both Poverty Oat-grass and Silky Oat-grass have V-shaped, pointed spikelets held at the tips of branches. The spikelets are tipped with awns that enhance the V-shape. Poverty Oat-grass can be identified by looking at the base of the plant where old, tan leaf remains form a curly mass on the ground. Silky Oat-grass has long, soft hairs on the sheath at the base of the stem.

V-shaped spikelets of Silky Oat-grass
(click to enlarge)

Curly remains of old leaves at the bottom of Poverty Oat-grass stems.
Photo by Dan Tenaglis, Missouriplants.com
(click to enlarge)

Hairy leaf sheath of Silky Oat-grass
(click to enlarge)

Black-seeded Needle Grass is common throughout the powerline but especially so along the eastern edge where it is in shade a good bit of the day. Elsewhere, look for it in upland woodlands and around rock outcrops. Needle Grass has very narrow leaves in dense clumps. The upper surface and margins of the leaves are rough–run your hand down the length of the blade and it will almost cut your skin. The flower cluster is open and airy and the spikelets are very distinctive–each is tipped with a dark brown seed bearing a long bristle–an awn up to 3 inches long. The bristle is both bent and spirally twisted. After the seed is shed, the bristle will twist and untwist in response to changes in humidity, eventually burying the seed in the ground. This is one of the most interesting seed dispersal stories around – if you’d like to know more, check out this 1900 article describing the mechanism (note: an older scientific name for this species is Stipa avenacea).

Seed of Black-seeded Needle Grass(click to enlarge)

A lot is going on botanically in the Nash Prairie this time of year besides cool-season grasses. Here are some of the wildflowers we saw in bloom:  

Venus' Looking Glass
(click to enlarge)

Small's Ragwort
(click to enlarge)

Summer Bluet
(click to enlarge)

Hairy Skullcap
(click to enlarge)

Smooth Spiderwort
(click to enlarge)

Pussytoes
(click to enlarge)

Nettle-leaf Sage
(click to enlarge)

Lespedeza (leaves only)

(click to enlarge)

Carolina Rose(click to enlarge)

Little Sensitive Brier(click to enlarge)

Yellow Star Grass(click to enlarge)

Smooth Beardtongue
(click to enlarge)

SUMMARY OF OBSERVED SPECIES:

Cherokee Sedge	Carex cherokeensis
Path Rush	Juncus tenuis
Orchard Grass	Dactylis glomerate
Daddy Longlegs	Order Opiliones
Meadow Fescue	Lolium pretense syn. Festuca pratensis
Witch Grass	Dichanthelium sp.
Little Barley	Hordeum pusillum
River Oats	Latifolium chasmanthium
Carex	Carex sp.
Smooth Spiderwort	Tradescantia ohiensis
Rescue Grass/Brome Grass	Bromus catharticus
Rye Brome	Bromus secalinus
Venus’ Looking Glass	Triodanis perfoliata
Black (Seeded) Needle Grass	Piptochaetium avenacea
Small’s Ragwort	Packera anonyma
Summer Bluet	Houstonia purpurea
Wingstem/Yellow Crownbeard	Verbesina occidentalis
Hairy Skullcap	Scutellaria elliptica
Pussytoes	Antennaria plantaginifolia
Velvet Witch Grass	Dichanthelium scoparium
Nettle-Leaf Sage	Salvia urticifolia
Silky Oat Grass	Danthonia sericea
Lespedeza (Native)	Lespedeza sp.
Carolina Rose	Rosa carolina
Little Sensitive Brier	Mimosa microphylla
Yellow Star Grass	Hypoxis hirsuta
Eastern Smooth Beardtongue	Penstemon laevigatus